Value

Napi::Value is the C++ manifestation of a JavaScript value.

Value is a the base class upon which other JavaScript values such as Number, Boolean, String, and Object are based.

The following classes inherit, either directly or indirectly, from Napi::Value:

• Napi::Array
• Napi::ArrayBuffer
• Napi::Boolean
• Napi::Buffer
• Napi::External
• Napi::Function
• Napi::Name
• Napi::Number
• Napi::Object
• Napi::String
• Napi::Symbol
• Napi::TypedArray
• Napi::TypedArrayOf

Methods

Empty Constructor

cpp Napi::Value::Value();

Creates a new empty Napi::Value instance.

Constructor

cpp Napi::Value::Value(napi_env env, napi_value value);

• [in] env: The napi_env environment in which to construct the Napi::Value object.

• [in] value: The C++ primitive from which to instantiate the Napi::Value. value may be any of:

• bool
• Any integer type
• Any floating point type
• const char* (encoded using UTF-8, null-terminated)
• const char16_t* (encoded using UTF-16-LE, null-terminated)
• std::string (encoded using UTF-8)
• std::u16string
• Napi::Value
• napi_value

From

cpp template <typename T> static Napi::Value Napi::Value::From(napi_env env, const T& value);

• [in] env: The napi_env environment in which to create the Napi::Value object.

• [in] value: The N-API primitive value from which to create the Napi::Value object.

Returns a Napi::Value object from an N-API primitive value.

operator napi_value

cpp operator napi_value() const;

Returns this Value's N-API value primitive.

Returns nullptr if this Napi::Value is empty.

operator ==

```cpp

bool Napi::Value::operator ==(const Napi::Value& other) const; ```

• [in] other: The Napi::Value object to be compared.

Returns a bool indicating if this Napi::Value strictly equals another Napi::Value.

operator !=

cpp bool Napi::Value::operator !=(const Napi::Value& other) const;

• [in] other: The Napi::Value object to be compared.

Returns a bool indicating if this Napi::Value does not strictly equal another Napi::Value.

StrictEquals

cpp bool Napi::Value::StrictEquals(const Napi::Value& other) const; - [in] other: The Napi::Value object to be compared.

Returns a bool indicating if this Napi::Value strictly equals another Napi::Value.

Env

cpp Napi::Env Napi::Value::Env() const;

Returns the Napi::Env environment this value is associated with.

IsEmpty

cpp bool Napi::Value::IsEmpty() const;

Returns a bool indicating if this Napi::Value is empty (uninitialized).

An empty Napi::Value is invalid, and most attempts to perform an operation on an empty Value will result in an exception. Note an empty Napi::Value is distinct from JavaScript null or undefined, which are valid values.

When C++ exceptions are disabled at compile time, a method with a Napi::Value return type may return an empty Value to indicate a pending exception. So when not using C++ exceptions, callers should check whether this Napi::Value is empty before attempting to use it.

Type

cpp napi_valuetype Napi::Value::Type() const;

Returns the napi_valuetype type of the Napi::Value.

IsUndefined

cpp bool Napi::Value::IsUndefined() const;

Returns a bool indicating if this Napi::Value is an undefined JavaScript value.

IsNull

cpp bool Napi::Value::IsNull() const;

Returns a bool indicating if this Napi::Value is a null JavaScript value.

IsBoolean

cpp bool Napi::Value::IsBoolean() const;

Returns a bool indicating if this Napi::Value is a JavaScript boolean.

IsNumber

cpp bool Napi::Value::IsNumber() const;

Returns a bool indicating if this Napi::Value is a JavaScript number.

IsString

cpp bool Napi::Value::IsString() const;

Returns a bool indicating if this Napi::Value is a JavaScript string.

IsSymbol

cpp bool Napi::Value::IsSymbol() const;

Returns a bool indicating if this Napi::Value is a JavaScript symbol.

IsArray

cpp bool Napi::Value::IsArray() const;

Returns a bool indicating if this Napi::Value is a JavaScript array.

IsArrayBuffer

cpp bool Napi::Value::IsArrayBuffer() const;

Returns a bool indicating if this Napi::Value is a JavaScript array buffer.

IsTypedArray

cpp bool Napi::Value::IsTypedArray() const;

Returns a bool indicating if this Napi::Value is a JavaScript typed array.

IsObject

cpp bool Napi::Value::IsObject() const;

Returns a bool indicating if this Napi::Value is JavaScript object.

IsFunction

cpp bool Napi::Value::IsFunction() const;

Returns a bool indicating if this Napi::Value is a JavaScript function.

IsBuffer

cpp bool Napi::Value::IsBuffer() const;

Returns a bool indicating if this Napi::Value is a Node buffer.

As

cpp template <typename T> T Napi::Value::As() const;

Casts to another type of Napi::Value, when the actual type is known or assumed.

This conversion does not coerce the type. Calling any methods inappropriate for the actual value type will throw Napi::Error.

ToBoolean

cpp Napi::Boolean Napi::Value::ToBoolean() const;

Returns the Napi::Value coerced to a JavaScript boolean.

ToNumber

cpp Napi::Number Napi::Value::ToNumber() const;

Returns the Napi::Value coerced to a JavaScript number.

ToString

cpp Napi::String Napi::Value::ToString() const;

Returns the Napi::Value coerced to a JavaScript string.

ToObject

cpp Napi::Object Napi::Value::ToObject() const;

Returns the Napi::Value coerced to a JavaScript object.